The 3rd generation (3G) mobile telecommunications system is a set of standards for the current generation of wireless telecommunications services, including mobile video, voice, and Web access applications. The Long Term Evolution (LTE) project was initiated by the 3rd Generation Partnership Project (3GPP) to address the next generation of 3G technology and architecture. LTE includes a number of improvements over the current generation of 3G systems including spectral flexibility, flexible wireless cell size and an all Internet protocol (IP) architecture. In particular, the IP architecture enables easy deployment of services such as video, voice, Web access, etc. The IP architecture also allows for simpler inter-working with other fixed and mobile networks.
In an LTE network, the IP architecture allows a wireless user equipment end-point (UE) to send and receive user packets through its designated public data network gateway (PDN-GW). The data path between the UE and the PDN-GW goes through an enhanced base station (eNodeB) and a server gateway (S-GW). When a UE data packet is received, the PDN-GW forwards the data packet to its intended destination. The PDN-GW also accepts packets on the behalf of the UE, and then forwards the arriving packets to the UE.
The logical connection between the UE and the PDN-GW is referred to as the Evolved Packet System (EPS) bearer (sometimes referred to herein as a “bearer”). Associated with each bearer are one or more traffic flow templates (TFT) and a quality of service (QoS) profile.
The TFT describe the criteria for whether a packet belongs to a bearer or not. The most commonly used TFT parameters are the IP addresses of the source and destination, the port numbers at the source and destinations, and the protocol type. Typically, all of these parameters are part of the header information of a packet.
A QoS profile governs how the packets of a bearer should be treated by the network. As a UE may have multiple concurrent sessions, each with different QoS needs, multiple bearers can be set up between a UE and the PDN-GW, each supporting a different QoS. Further, multiple sessions of the same QoS class can be mapped onto the same bearer.
When a UE is first attached to the network, a default bearer, with a prescribed QoS, may be set up between the UE and the PDN-GW. Other bearers, referred to as dedicated bearers, can be set up and torn down on an “as needed” basis.
Multicast applications are one important class of applications for LTE networks where traffic from a source may be sent to a selected plurality of UEs or to all UEs (in broadcast mode). Examples of multicast applications are conference calls, push-to-talk (PTT) group calls, and multiple end-point media distribution (e.g., video conferences).
Multicast applications can be supported through the use of multiple unicast logical connections, however, this is not efficient in terms of both processing at the source and network utilization. With unicast, the source has to send the same packet to each destination. This increases the need of processing power at the source. For example, the same packet may traverse the same link and appear multiple times at the same network nodes, consuming bandwidth, particularly for the access link between the source and the network.
Therefore, in order to support multicast applications, multicast routing protocols have been developed for activating the routers in IP networks. For example, a multicast routing protocol may allow a router to inform its neighbors of the multicast traffic that it is currently receiving; and the multicast traffic that it wants to receive.
The multicast routing protocol may also regulate the propagation of multicast traffic between routers in IP networks. Currently, one popular multicast routing protocol is Protocol Independent Multicast-Sparse Mode, RFC 4601 (PIM-SM). In general, PIM-SM is very efficient in bandwidth as a router (i) only forwards the traffic of a multicast group to a neighbor if the neighbor requests such traffic, and (ii) may request traffic from a multicast group from only one of its neighbors. PIM-SM also supports general multicast in that it allows any member of a multicast group to transmit (i.e., be a source), even concurrently. Another currently popular multicast routing protocol is Source Specific Multicast, RFC 4607 (SSM), where a multicast group has only a single source.
While useful for their intended purposes, multicast routing protocols such as PIM-SM and SSM are complex and require the support of a substantial amount of processing power. For example, PIM-SM and SSM multicast packets are often duplicated at routers, which tends to require additional processing for managing the increased throughput. Therefore, a method is needed for setting up IP multicast transmissions over an LTE network that would improve the throughput of a router.